Transcript Protozoa
Medical Parasitology Hugh B Fackrell Parasitic eukaryotes protozoa Platyhelminthes (flatworms) Trematodes (flukes) Nematodes (roundworms) Cestodes (tapeworms) arthropods protozoa: most important in warmer climates do not elicit a strong antibody response (some exceptions) diagnosed by microscopic means no vaccines humans are intermediate hosts Protozoa - two forms Trophozoite: active, growing - causes disease Cyst: dormant, resistant form - increases survival of protozoa and extends transmission Intestinal & Urogenital Protozoa Amebae Flagellates Ciliates Coccidia Microsporidia Amebae Sarcodina Sarcodina: Entamoeba histolytica amoebiasis (amoebic dysentry). only the cyst stage is infectious. disseminated amoebiasis - abscesses in the liver, can be fatal, diagnosed serologically. person not infectious when gut contents moving fast, cysts form when it slows down. Sacrodina: treatment tetracycline & diloxanide furoate. metronidazole. usually includes choloroquine. Infections by Free Living Amaeboe Naeglaria • Acathamoeba Naegleria: found in freshwater lakes or streams causes encephalitis in swimmers - can be fatal (rare). Acanthamoeba: found in soil, fresh and brackish (1/2 salt) water ubiquitous can infect contact lens not properly cared for - infection of cornea, reduced vision. enucleation: complete removel of the eyeball Flagellates Trichomoniasis: Trichomonas vaginalis - millions of cases sexually transmitted - trophozoite inhabits the vagina and urethra. males have very little irritation. female, vagina becomes alkaline, allows the bacteria to overgrow that are usually suppressed by acid - symptoms include odor, discharge, itching and burning. Treatment: metronidazole, Flagyl. Blood & Tissue Protozoa Plasmodium Babesia Toxoplasma Sacrocystis Pneumocystis Leishmania Trypanosoma Giardiasis: Giardia lamblia fecal/oral transmission. the cyst form is very resistant to destruction. infection of upper small instestine, can be asymptomatic. most common protozoal infection in the U.S. Mastigophora: flagellates - con’t Gastroenteritis: diarrhea, dark, greasy, foul feces. abdomenal discomform, flatulence, anorexia, weight loss. lasts two-three weeks followed by recovery. chronic - intermittent diarrhea. Transmission: water - treated and untreated. common in daycare centers Trypanosomiasis: Trypanosoma brucei gambiense (African sleeping sickness). Trypanosoma brucei rhodesiense. South American sleeping sickness (T. cruzi). Chaga’s disease. reservoir in Africa: cattle, swine & wild animals. infected by the Tse Tse fly bite legion South American Sleeping Sickness T. cruzi: reservoir dogs, cats & wild animals. vector reduvid bugs - defecate when biting introduce trypanosomes. can be spread by hands from bite to eyes, conjunctivitis. no treatment. Prevention: control insects. Leishmaniasis: Sand flies • a) cutaneous • b) viscerotropuie (clinical note) 12 million cases fever, chills & sometimes gastrointestinal involvement. bone marrow aspects - cultures also serodiagnostic techniques. Malaria Plasmodium vivax, P. falciparum and P. ovale. 100,000,000 cases spread by Anopheles mosquito 1 million deaths per year in the tropics and sub-tropics. life cycle of protozoa in the mosquito and the human control the transmission and the disease. Pneumocystosis Pneumocystis Pneumocystis carinii - Thought to be a protozoan but recent RNA analysis has shown it to be a fungus. Infections occur world wide, if symptoms occur - mild respiratory. Childhood. Pneumocystosis cont. Respiratory Infection interstitial pneumonitis with plasma cell infiltrates Treatment Trimethoprim - sulfamethoxazole Aerosolized pentamidine (particularly for Sporozoa Malaria: Plasmodium vivax, P. falciparum and P. ovale. 100,000,000 cases spread by Anopheles mosquito 1 million deaths per year in the tropics and sub-tropics. life cycle of protozoa in the mosquito and the human control the transmission and the disease. Nematodes: Roundworms Pinworm Roundworm Ascaris Whipworm Hookworm Threadworm etc Coccidia Cryptosporidiosis Intestinal disease Zoonotic, and person-to-person Cryptosporidium Coccidia cont. Laboratory Diagnosis Fresh, or formalin-treated stool Microscopic - direct smear stain - fluorescent antibody Oocysts - concentrated from stool of persons with diarrhea Treatment flatworms (platyhelminthes) arthropods DONE!!!